Sous-vide is a method of cooking that is intended to maintain the integrity of food by heating the food for an extended period of time at a relatively low temperature. The food is cooked for a long time, sometimes over 24 hours. Unlike cooking in a slow cooker, sous-vide cooking uses airtight plastic bags placed in hot water at a temperature well below the water's boiling point (e.g., around 60° C. or 140° F.). Sous-vide cooking, however, often requires precise temperature control of the heated water. Differences of even one degree can affect the finished product. Consequently, commercially available Sous-vide cookers are expensive water-bath machines that use thermal immersion circulators to circulate precisely heated water. There exists a need for Sous-vide cookers that can be made at low cost and provide precise temperature control.